Abstract:
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Purpose: Post-exercise/pharmacological pulmonary uptake of Thallium-201 is an index of left ventricular dysfunction and/or multi-vessel disease, also associated with poor prognosis. More recent studies have also reported that lung uptake of Tc-99m MIBI correlated with severe coronary artery disease(CAD)and reduced left ventricular function. No prior publication of diffuse Tc-99m MIBI lung uptake and/or comparison between smokers and non-smokers has been performed. The purpose of our study was to determine if a difference in pulmonary uptake of Tc-99m MIBI exists between these two patient populations.
Methods and Materials: Resting and stress lung to heart ratios (LHR) were retrospectively determined in 144 selected patients who underwent Tc-99m MIBI myocardial perfusion testing. 72 were non-smokers (4 males and 68 females, age range 30-86 yr., mean 64 yr.). A second group comprised of 72 smokers (32 males and 40 females, age range 37-83 yr., mean 60 yr.). Their respective chest X-rays were reviewed. The anterior view of the SPECT projection data set was identified and the adjacent projections (one on either side) were summed to increase count statistics. The LHR was determined by dividing the mean lung counts by the maximum myocardial counts using a 10 pixel rectangular ROI. Basic statistical analysis was performed to compare both groups using a 2-tailed Student's t test and a p < 0.05 is taken to indicate a statistically significant result.
Results: Overall, the non-smoker group had higher lung uptake than the smoker group (p < 0.05). There was no statistically significant difference in lung uptake in those patients with positive or negative results for CAD in either group. This is in agreement with some of the published results in the literature. Those patients determined to be positive for CAD, as well as those that were negative for CAD had consistently higher lung uptake in the non-smoker group when compared to the smoker group. This correlated well with chest X-ray findings of COPD.
Conclusion: In general our findings showed that lung uptake was significantly lower in the smoker group when compared to the non-smoker group, presumably due to less viable lung tissue available because of the damage caused by long term smoking. Perhaps this may help explain some of the contradictory reports of MIBI lung uptake. No significant higher post exercise lung uptake was found in those patients with CAD.
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Sebastian MD, M,
Increased Pulmonary Uptake of TC-99 Sestamibi (MIBI) during Myocardial Perfusion Testing in Non-Smokers. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3101111.html
